Amazon changed the game when it offered 3G access in its Kindle e-readers at no charge. That connection is great to have, but those who use it to browse the web won't be happy: Amazon now limits that Internet on-ramp to just 50 MB per month.

Arguably, one of the best features of Amazon’s Kindle e-readers with 3G is free, unlimited mobile broadband. Device owners can use the connection for downloading e-books when out of Wi-Fi range and can also use the web through an experimental browser. The free Internet ride is over though: Amazon is now capping use of the browser over 3G at 50 megabytes per month.

The change, first noticed by a MobileRead forum member, only impacts the browser. Kindle 3G owners can still download as many books as they want from Amazon, for example, or browse over Wi-Fi. Surfing the web on Amazon’s dime, however, is now limited.

The new policy won’t likely impact the majority of those who own a Kindle 3G, as the browser experience isn’t optimal due to the electronic ink display. But those who rely on that free 3G connection for checking Facebook, e-mail or various web sites won’t be able to do so as much; 50 megabytes is a pretty paltry amount of bandwidth.

My first thought was that Amazon is simply trying to limit the costs it pays for 3G service or perhaps it wants to push sales of the Kindle Fire; even though that tablet only has Wi-Fi, the browsing experience is far better. However, it’s more likely that Amazon is limiting the 3G connection because of hacks that allow the device to be used as 3G mobile hotspot for free.

If you can use a Kindle Keyboard 3G as a hotspot at no extra charge, chances are, you’ll use the connection heavily. While Amazon is paying operators for the 3G service, it’s not likely paying enough for device owners to use the mobile broadband as a primary — and free — mobile on-ramp to the web.